McMaster professor finds that plants take care of their families

Plants are good to their family. McMaster professor Susan Dudley discovers that plants are more inclined to help their siblings than unrelated plants.
Amanda File (left) and Susan Dudley (right) working in the greenhouse at McMaster University. (Anna Rothschild/WGBH Educational Foundation)

You might never look the same way again at your Hooded Skullcap (Scutellaria galericulata).

A McMaster professor has discovered that plants take care of their families.

Susan Dudley, a biology professor at McMaster University, spoke with CBC Radio's As It Happens about a 2012 study she conducted that found certain kinds of plants will take better care of their siblings than stranger plants.

"Plants live closely with other plants," said Dudley. "They often disperse really locally, so they have the opportunity to interact with siblings, and evolutionary theory tells us that benefitting a relative is the way to increase your own fitness, whether you're an animal or a plant."

Describing 'sibling plants' as being seedlings from the same mother plants, Dudley and her graduate student, Amanda File, grew ragweed plants in groups of siblings as well as in groups of strangers and inoculated half of them with a symbiotic variety of fungus.

Study: Plants take care of their own

Dudley said the sibling groups had a much better developed soil network than the stranger plants did, which demonstrated the plants' need to take care of their own.

"It is, in the long run, selfish, in that your siblings share your genes, so by benefitting your siblings, that increases the fitness of the plant," said Dudley. "It's not pure altruism, but that willingness to take better care of your family because their fitness also extends your fitness."

Dudley said this tells us that plants can sense and respond, and although plants are not necessarily intelligent, this study shows us that there is much more going on in plants than previously thought. She added that this kind of motivation to protect one's family is seen in animals as well.

"Where we see helpers of the nest in birds and fish, or where we see alarm calls in birds and squirrels, we often see it associated with relatedness," said Dudley. "You might warn your relatives but you're not going to warn strangers."

Dudley and File's study will go on to test ragweed in the field to see whether plants will continue to take care of their own.